How do I put my form fields in my database?

To put the fields you've just created in the form into the database, simply go to the "Participants" tab, click on the 3 small dots at the top right and then on the last field of the drop-down menu "Modify columns". Once you've done this, all the fields you've created in the form will be added to the database by clicking on the "+ ... form fields" at the bottom of the page, where "..." corresponds to the number of fields to be added.